The following relates to the optical arts. It is described with particular reference to example illustrated embodiments relating to optical Fabry-Perot filters configured for operation in the visible or near infra-red wavelength range, and with reference to example illustrated embodiments relating to imaging sensors employing same. However, the following finds more general application in Fabry-Perot filters operating in wavelength ranges other than the visible and near infra-red, and in manufacturing methods for making Fabry-Perot filters, and in diverse applications employing Fabry-Perot filters, such as digital photography, electrophotographic printing, tunable color filters, wireless communications, and so forth.
Tunable Fabry-Perot filters provide operative capabilities including high Q filtering, precision wavelength tuning, and the ability to perform rapid spectral sweeps. Tunable Fabry-Perot filters configured for operation in the visible and/or near infra-red wavelength range have applications in imaging, fiber optical communication systems, and so forth. However, fabrication of Fabry-Perot filters for these wavelength ranges is difficult. The optical wavelength range is about 400-700 nm; accordingly, a tunable Fabry-Perot filter usable for color measurements or filtering typically has a tunable gap of about 300 nm with a tunable precision of about 10 nm. Low voltage operation is also desirable for certain applications, such as portable battery-powered devices.
Micro-electromechanical systems (MEMS) devices have been used to fabricate tunable Fabry-Perot filters for use in the visible or near infra-red range. However, difficulties have been encountered, including warping-induced filtering errors, fragility of the thin optical membranes sometimes used in such devices, manufacturing processes that are time consuming, labor-intensive, and/or costly, undesirably high operating voltages for achieving the tuning, and so forth.